System and method for removing volatile vapors from containers

ABSTRACT

A system is configured to remove volatile organic compounds from a container. The system includes an enclosed contactor vessel having a first inlet to receive vapor containing volatile organic compounds from the container and a second inlet. The second inlet receives a vapor capture medium from a source. A contactor facilitates entrainment of the volatile organic compounds with the vapor capture medium while a first outlet recirculates treated vapor back to the container to effect a closed loop.

RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.12/634,583, filed Dec. 9, 2009, entitled SYSTEM AND METHOD FOR REMOVINGVOLATILE VAPORS FROM CONTAINERS, which is a Continuation-In-Part of U.S.patent application Ser. No. 11/959,416, filed Dec. 18, 2007, entitledSYSTEM AND METHOD FOR REMOVING VOLATILE VAPORS FROM CONTAINERS, now U.S.Pat. No. 7,727,310 and claims benefit of priority to Provisional U.S.Patent Application No. 60/871,766, filed Dec. 22, 2006, entitledDEGASSING SYSTEM AND TECHNIQUE; the aforementioned priority applicationsbeing hereby incorporated by reference in their entirety.

BACKGROUND

The problem of removing volatile vapors has significance in manyapplications, including those that require transfer of fuel. When a fueltank is emptied, vapor fuels can build up in the tank. In addition tobeing an inherent safety hazard, the vapors can interfere with fluidintake in refill operations. In order to empty tanks and containers offuel vapors, conventional techniques sometimes seek to burn the vaporfuels. However, with emission control laws and regulations becoming morestrict, the amount of vapor fuel that can be legally burned or flaredhas decreased.

Current conventional techniques for dealing with the buildup of volatilevapors provide for destructive solutions. Specific conventionalapproaches include oxidizing, flaring or burning the vapor contents ofemptied tanks and containers. But these conventional approaches oftenhave environmental consequences. Moreover, with increasing fuel costs,none of the vapors that are in emptied tanks are captured.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a system for use in cleansing containers of volatileorganic compounds, under an embodiment.

FIG. 2 illustrates a technique or methodology for removing VOC vaporsfrom containers, under an embodiment of the invention.

FIG. 3A is a side view of a container system 300 for use in removing VOCfrom tanks and containers, according to an embodiment.

FIG. 3B illustrates a top view of the container of system 300, under anembodiment.

FIG. 4 illustrates a system that removes or cleanses a fuel tank orother storage unit of volatile organic compounds and then recaptures theVOC vapors in liquid form, according to an embodiment of the invention.

FIG. 5 illustrates a further embodiment of a system 500 that recoversvolatile organic compounds from a container, similar to FIG. 4.

FIG. 6 illustrates a contactor vessel for use in the system of FIG. 5.

DETAILED DESCRIPTION

Embodiments described herein enable a system and method by whichvolatile organic compounds (VOCs) and other volatile vapors may beremoved from various types of containers and tanks. Among otherbenefits, embodiments described herein enable a system or technique forcleansing or removing VOCs from emptied tanks and containers withoutneed to flare, burn or oxidize the VOC vapors in the emptied tanks.Still further, embodiments described herein enable the VOCs within theemptied tanks to be captured and re-used. In fuel applications, forexample, the recapture of fuel from vapors is conservative andcost-effective.

According to an embodiment, a system is configured to remove VOCs from adonative tank or container. The system includes a vapor capture medium,and a particulatizer that are provided in a separate containment. Theparticulatizer is positioned to (i) receive VOCs that are removed fromthe container in a vapor flow, and (ii) introduce the VOCs into thevapor capture medium as micro-sized particles. The vapor capture mediumis in liquid form and has a composition that is inherently attracted tobond with at least some of the VOCs that are removed from the containerin the vapor flow, so that the vapor capture medium captures at leastsome of the micro-sized particles of VOCs that are introduced throughthe particulatizer.

An embodiment provides that VOCs may be removed from a container bysteps that include receiving a vapor flow from a container that is atleast partially emptied to include VOC vapor. The VOCs in the vapor flowmay be particulatized into micro-sized particles. The micro-sizedparticles may then be introduced into a vapor capture medium that is inliquid form. The vapor capture medium may have a composition that isinherently attracted to bond with at least some of the VOCs that arereceived in the vapor flow, so that the vapor capture medium captures atleast some of the micro-sized particles.

In one embodiment, the introduction of the micro-size particles is doneplanarly, so as to span a plane of an interface of the vapor capturemedium. More specifically, the micro-sized particles are introduced intothe VCM across a planar interface that corresponds to an area thatunderlies the VCM.

Still further, an embodiment includes a fuel recapture system. Thesystem includes an intake and a container that combine to receive avapor flow of fuel from a donative container that is at least partiallyemptied. The container includes a chamber that initially receives thevapor flow, and a micro-porous layer that particulatizes the flow offuel vapor into micro-sized particles. The container also includes aquantity of liquid that forms a vapor capture medium. The vapor capturemedium is positioned to receive the particles from the micro-porouslayer. Additionally the vapor capture medium includes a composition thatis inherently attracted to bond with molecules of fuel vapor, so as tocapture micro-sized particles of fuel vapor that comprise at least aportion of the particles particularized from the flow of fuel vapor.

A further embodiment includes a system for recovering volatile organiccompounds from a container. The system includes an enclosed contactorvessel having a first inlet to receive vapor containing volatile organiccompounds from the container and a second inlet. The second inletreceives a vapor capture medium from a source. A contactor facilitatesentrainment of the volatile organic compounds with the vapor capturemedium while a first outlet recirculates treated vapor back to thecontainer to effect a closed loop.

The term “micro-size” or variations thereof refers to an upper limit indimension of a particle. Generally, a “micro-size” particle means aparticle that has a dimension that is less than 500 microns. However, asthe term is intended to mean an upper-limit, micro-sized particles mayalso include particles that are smaller than the order of the micron(e.g. nano-scaled).

As used herein, the terms “particulatizer” or variations thereof (e.g.“particulatizing”) mean something that performs the act of makingparticulate, including micro-size particles.

System Overview

FIG. 1 illustrates a system for use in cleansing containers of volatileorganic compounds, under an embodiment. A system 100 may be implementedthrough a container, or series of containers, that is transportable orotherwise combinable on-site with a tank 140 or other storage unitcontaining VOCs. The tank 140 may be a container for use in holding fueland other volatile substances for anyone of many applications.Accordingly, the tank 140 may have any one of many possible sizes andscale of operation. For example, the tank 140 may correspond to a fuelstorage tank having a size or scale that ranges anywhere from hundredsof gallons to millions of gallons. One application for an embodimentsuch as described is to remove vapors or other fuels from large capacitytanks, such as 1-3 million gallon tanks. Other applications may includeremoving vapors from smaller tanks that hold thousands of gallons andare used at different sites for fueling equipment or vehicles. Stillfurther, system 100 may be employed with a fuel tank or vacuum tankvehicle or ship tanker, or for the fuel tank of an aircraft. Numerousother applications for implementing embodiments such as described arecontemplated, some of which are described elsewhere in this application.

System 100 may be coupled to a tank 140 containing volatile organiccompounds (VOC) that need to be removed. Some examples of VOC vaporsthat may be handled with system 100, and other embodiments describedherein, include vapors of gasoline, kerosene, crude fuel, butane,octane, Hexane, Pentane, LPG, LNG and other volatile fuels. Stillfurther, embodiments described herein may alternatively be used toremove volatile chemical vapors such as alcohol, amines, ketones,benzenes, toluenes, xylene, and ethyl benzene.

If tank 140 is emptied or partially emptied, the presence of VOC vaporsand residue creates a potential hazard. Moreover, the VOCs must besufficiently removed from the tank 140 so as to not hinder the tank whenbeing refilled. System 100 may be combined (i.e. as part of the sameunit) or coupled (i.e. as part of a separate unit) to the tank 140 toenable the VOC vapors 140 to be sufficiently removed. The sufficiency ofthe removal may be set by pre-determined criteria, such as by governmentregulations or desired levels. Depending on the application, thecontainer 140 may correspond to a large capacity fuel tank for servicinga population (e.g. such as found with refineries), a small storage fueltank for servicing a particular site, or vehicle/shipping fuel tankers.In general, system 100 may be used to cleanse and optionally recaptureVOCs that are in the form of fuel vapor from an empty or nearly emptycontainer.

In contrast to conventional approaches that oxidize, burn, or flare theemptied or partially emptied tanks of VOCs, system 100, and otherembodiments described herein, captures the VOCs in a non-destructivemanner. Still further, the capture of the VOCs may be combined with asub-system to enable isolation and reuse of the VOCs in liquid form.

According to an embodiment, a system 100 includes a particulatizer 110and a vapor capture medium 120 (VCM). The particulatizer 110 receivesthe VOC vapor 102 and causes the VOC vapor 102 to particularize intomicro-size particles 112. The micro-sized particles 112 may vary inrange between 5-500 microns, although smaller and larger particles mayalso be used with embodiments described herein. For example, particles112 of VOCs may be introduced into the VCM 120 that has a dimension thatis of the order of 500-1000 or more microns. Likewise, even smallerdimensioned particles (e.g. “nano-scaled” particles such as 0.01-0.5microns) may be created from the VOC vapor and introduced into the VCM120.

In an embodiment, the VCM 120 is formulated or otherwise created toretain particles 112. To this end, the VCM 120 may be in liquid form andhave a composition that is inherently attracted to bond with chemicalsthat comprise the VOC vapors 102. The particulatizer 110 may particulatethe VOC vapors 102 to enhance or maximize the absorption amount that ispossible from a given quantity of the VCM 120. In one embodiment, theVOC particles 112 have a largest dimension that is in range of 1-150microns, although as mentioned above, the micro-sized particles 112 maybe made to have smaller or larger dimensions to accommodate differentflow rates.

In addition to particularizing the VOC vapor 102, the particulatizer 110(with or without other components) also distribute the particles intothe VCM 120. In one embodiment, the particulatizer 110 is provided inthe form of a micro-porous pipe or containment that is inserted into orotherwise surrounded by the VCM 120. For example, a pipe or tubing maycarry VOC vapor 102 and be made to include high-density, micro-porouswalls or sections that serve to distribute the VOC particles 112 withpressure supplied from the tank 140 and/or other sources. Such a pipemay span the VCM 120 vertically and/or horizontally. For example,high-density pipes or tubing may be extended into the VCM 120, and/ortraversed horizontally on the bottom of the containment of the VCM.

In an embodiment, however, the particulatizer 110 is constructed andpositioned to planarly distributes the VOC particles 112 into the VCM120. Specifically, the VOC particles 112 may be introduced into anarea-interface with the VCM 120, so that the particles 112 areintroduced substantially uniformly across a plane that defines the area.One or more embodiments recognize that such planar distribution enhancesor maximizes the saturation of VCM 120 with VOC particles 112. Forexample, consistent with an embodiment shown by FIG. 3, theparticulatizer 110 may be provided as a layer that is positionedunderneath the VCM 120. The particulatizer 110 may use a combination ofVOC vapor pressure and gravity to enable the VOC particles 112 to beplanarly distributed into the VCM 120.

According to an embodiment, the VCM 120 has characteristics of beingnon-volatile, with the ability to capture and hold carbon compounds. Inone embodiment, the VCM 120 has the capability of capturing and holding(on a molecular or particle level) elements of the source vapor.Additionally, the VCM 120 has the characteristic of being substantiallyor at least measurably separable from the source vapor particles 112.

In an embodiment, the VCM 120 is selected or formulated based on itscapacity to retain the VOC particles 112. Under one embodiment, the VCM120 may be selected to be a naturally derived, non-volatile oil with acomposition that has an inherent affinity for carbon molecules in fuelor other volatile compounds. In particular, the attraction may be toinherently form covalent bonds with the carbon present in the VOCs.Accordingly, an embodiment provides that the VCM 120 is formulated orotherwise derived from tall fatty acids, such as botanically derivedoils and/or animal fats. Specific examples of materials that may be usedin the composition include soybean oil, palm oil, cotton seed oil, lemonoil, and/or lavender. One or more embodiments provide for the VCM 120 tobe prepared or derived from a raw state.

While embodiments described above provide for use of botanically-derivedoils, for example, other embodiments contemplate other formulations forVCM 120. In one embodiment, the VCM 120 may be derived or otherwisebased on bio-diesel. Still further, other embodiments provide for use ofa honeycomb solid structure that has some absorbency to retain and holdvapors, particularly from carbon-based volatile compounds.

An embodiment provides that the VCM 120 may be saturated with the VOCcompounds present in the particles 112. Saturated (or contaminated) VCM122 may be removed from the system 100. In one embodiment, the saturatedVCM 122 may be cleansed and re-used through a recapture system orprocess 130. The recapture system or process 130 may correspond to asystem or process that separates the VCM 120 from the VOC compoundspresent with particles 112. For example, a combination of chilling andheating may be used to separate VOC compounds from the particles 112 asan alternative, a centrifugal process may be used. Still further,another recapture process or system is illustrated with an embodiment ofFIG. 4.

In an embodiment, recaptured VOCs 132 result from the recapture system130 or process. The recaptured VOCs 132 may be re-used in liquid form.Thus, for example fuel vapors may be recaptured as liquid fuel and thenre-used.

Additionally, cleansed VCM 134 may result from the re-captured process.The cleansed VCM 134 may be re-introduced into the system 100 for re-useas VCM 120. Under one implementation, the cleansed VCM 134 is sparged orcleansed further before re-use. In a passive system, the VCM 120 may bedistilled and cleansed off-site. In an active system, valves and/orpipes may be used to re-circulate the cleansed VCM 134 back into thesystem. In particular, the re-circulation may occur while the VOCremoval process is ongoing. Considerations for pressure balancing andother factors may be integrated into how valves that interconnectcontainers of cleansed VCM 134 feedback into the containment of VCM 120.

One or more embodiments anticipate that some VOC particles 112 passthrough the VCM 120 without capture (“residue vapor 136”). In anembodiment, the composition and quantity of VCM 120 is selected so thatthe residue VOC vapor 136 is below a pre-determined or desired threshold(e.g. below government regulations). If the VCM 120 is held incontainment, the residue VOC vapor 136 may be released or suctioned offelsewhere. As an alternative or addition, the VOC vapor 136 may bereturned to the tank 140 for additional processing.

In one embodiment, the system 100 is coupled to the container 140 tocreate an active and closed system that neither releases nor destroysVOCs. In such an embodiment, the residue VOC vapor 136 is passed backinto the tank 140. The residual VOC vapor 136 may be re-subjected to theprocess performed by system 100, resulting in additional capture of VOCparticles 112.

Methodology

FIG. 2 illustrates a technique or methodology for removing VOC vaporsfrom containers, under an embodiment of the invention. In performing amethod such as described, reference may be made to elements of system100 for purpose of illustrating suitable components or elements for usein performance of a step or sub-step being described.

Step 210 provides that liquid VCM material is prepared for use. In oneembodiment, the liquid VCM 120 may be a botanically-derived (oranimal-derived) tall fatty-acid composition. Some processing may beperformed on a raw oil to prepare it for use as VCM 120. In oneimplementation, a selected composition of botanically-derived oil ismixed with a natural biocide component such as lavender or lemon oil.Either component may provide the benefit of scenting the VCM 120. Themixture may be sparged, meaning air or air bubbles is finely introducedinto the mixture. This may be accomplished by placing the oil/liquidmixture on pipes or ducts with microscopic porosity. Air may be runthrough the pipes so as to be introduced as small bubbles into themixture. The sparging process may be enhanced by maintaining thetemperature of the oil undergoing the process at about 80 degreesFahrenheit, or thereabouts. Among other benefits, the sparging processresults in cleansing or removal of naturally present volatile compounds.

Separately, under an embodiment, step 220 provides that the tank 140 isprepared for use. In one implementation, natural scent oils or agentsmay be introduced into the tank 140 in order to confirm withdrawal ofVOCs when the system 100 is installed.

In step 230, the system 100 is enabled for operation with the tank 140.The intakes from system 100 may be connected to an appropriate VOCinterface of the tank 140. In many applications, the VOC interface 140may correspond to valves or pipes that are used to release VOCs from thetank. Depending on the application and the conditions present, thesystem 100 may receive a passive flow of vapor through the intake withthe tank 140. The passive vapor flow may be an inherent result ofintroduction of fuel or liquid compounds into the tank. Alternatively,the passive vapor flow may result from a combination of the tank beingheated by sunshine or other environmental conditions. In applicationswhere the tank 140 is large, or conditions are not favorable for passiveflow, turbines or other equipment may be used to draw the VOC vapor 102out and into system 100.

According to an embodiment, step 240 provides that a determination ismade that recapture is to be performed. This determination may beresponsive to one or both conditions of (i) the tank 140 beingsufficiently emptied of VOC vapors (as determined by some pre-determinedthreshold), or (ii) the VCM 120 of the system 100 being saturated. Inone implementation, for example the VCM 120 is capable of holding up to5-10% of its weight in VOC compounds through the introduction of VOCparticles 112. Depending on the composition, the amount of VOC particlesthat can be handled may be even more than 10%. Thus, through measurementof weight of the VCM 120 or a container in which system 100 isimplemented, a determination may be made as to whether recapture shouldbe performed. Additionally, the levels of residue VOC vapors 136 may bemeasured to determine whether the VCM 120 is to be recaptured.

While embodiments contemplate that system 100 may cleanse tank 140 toadequate levels of VOC, one or more embodiments provide that recaptureis performed before the tank 140 is sufficiently cleansed. Stillfurther, recapture may also be performed each time cleansing iscompleted in order to reintroduce the VOC in liquid form to the tank140.

Accordingly, an embodiment provides that the recapture process isperformed in step 250. A system for performing a recapture process isdescribed with an embodiment of FIG. 4, as well as elsewhere below. Inembodiment, a result of the recapture process is one or both of (i) thecaptured VOC in liquid form, and/or (ii) sufficiently cleansed VCM 120for re-use.

Container System

FIG. 3A is a side view of a container system 300 for use in removing VOCfrom tanks and containers, according to an embodiment. The containersystem 300 is provided within a container housing 310 that includes areceiving containment 320, a micro-porous layer 330 (or other plenarylayer), and a chamber 340 for holding a VCM 342 and residue space 344.An intake 312 may extend from a top end 311 of the container housing 310and form a channel 313 which feeds into the receiving containment 320.The receiving containment 320 may be provided as an open space beneathboth the micro-porous layer 330 and the chamber 340. This orientationenables the system 300 to benefit from gravity when the VOCs areintroduced into the VCM 342. As mentioned with one or more otherembodiments, the micro-porous layer 330 may be replaced or supplementedwith high-density, micro-porous tubing or piping (extending verticallyor horizontally).

The intake 312 may extend and connect to a tank or other container thatis to be cleansed of VOC. In an embodiment, vapor flow 302 containingVOCs is fed through intake 312 and received in the receiving containment320. Depending on the application, the vapor flow 302 may be driven byoptional turbines or other drivers 315, so as to be an active intake.Alternatively, the vapor flow 302 may be generated passively, through,for example, changing conditions in the donative container. For example,in the case of storage containers, exposure to sun and heat maysufficiently increase the pressure of the container being cleansed todrive the vapor flow 302 through the intake 312 and into the receivingcontainment 320. In each case, the vapor flow 302 contains sufficientpressure to drive VOC compounds in the vapor from the receivingcontainment 320 through the micro-porous layer 330 and into the VCM 342.

Thus, in some applications, passive forces in the introduction of thevapor flow 302 provide sufficient pressure to drive the VOCs upward fromthe receiving containment 320 through the micro-porous layer 330, asdescribed. In addition to increase in temperature (such as from subexposure), passive forces for driving the vapor flow 302 may arise fromthe introduction of liquid compound into the donating tank.

The micro-porous layer 330 serves to particularize the vapor flow 302,while distributing particles arising from the vapor flow across a largearea interface (i.e. the bottom boundary of the VCM 342) with the VCM342. As such, the micro-porous layer 330 in the container housing 310provides an implementation of particulatizer 110 (FIG. 1). According toan embodiment, the micro-porous layer 330 is formed from plastic orother molded material, such as ultra high molecular weight polyethylene(UHMW PE). The composition of the micro-porous layer 330 may also bechemically inert, at least to the VOCs that are introduced into thelayer. The micro-porous layer 330 may be implemented throughcommercially available products typically used for functions such asdiffusing, aerating and fluidizing materials. An example of amanufacturer of such products is GENPORE, a division of GENERALPOLYMERIC CORP. Sealants such as silicone may be used to seal themicro-porous layer 330 in place over the receiving containment 320. Theplate(s) that comprise the micro-porous layer 330 may be sealed in placewith standard RTV Silicones or the equivalent. In one implementation,the micro-porous layer 330 utilizes micro-dimensioned pores in the rangeof 10-125 microns. As an alternative implementation, a stainless steelplate that is laser drilled with micro-sized pores may also be used forthe micro-porous layer 330.

As mentioned with other embodiments, much of the VOC particles that passthrough the micro-porous layer 330 are captured in the liquid mediumthat is the VCM 342. Some VOC particles pass through the VCM 342 andoccupy the space 344 of chamber 340. The VCM 342 may be designed andselected so that the concentration of such vapor residue in the space344 is below some desired or required threshold (such as may be requiredby government regulations). An outlet 348 maybe used to collect andremove such VOC residue from space 344. A vacuum (not shown) or otherdriver may be used to pull the VOC particles (which should be at lowconcentration) out of the space 344. As described with an embodiment ofFIG. 2, for example, the residue VOC vapor may be passed back into thedonative container, so that the use of system 300 remains closed andnon-destructive.

As the VCM 342 saturates with use, the captured VOC may separated andremoved from the mixture in a separate process or sub-system. In oneembodiment, the result of the recapture is that the VCM 342 issubstantially restored to its original condition (so that it can bere-used) and the previously captured VOC in the mixture is in isolatedliquid form. In the case of fuel, for example, the recapture of the VOCfrom the VCM 342 provides a cost-savings and is environmentallybeneficial.

In an implementation, one or more drains 352 may be provided to drainthe container housing 310 of the VCM 342. The VCM 342 may be drainedwhen, for example, the VCM is saturated or when the VOC removal from thedonative tank is sufficiently removed.

FIG. 3B illustrates a top view of the container of system 300, under anembodiment. The particular shape of the container may be circular orrectangular. The top side 311 of the container housing 310 may providethe entry for intake 312, and the outlet 348 by which the VOC residue isexited from the container housing.

As mentioned, an embodiment provides that the micro-porous layer 330planarly introduces particles of VOC into the VCM 342. In an embodiment,the micro-porous layer 330 spans an internal area of the containerhousing 310, shown by dimensions a and b. In one embodiment, theparticles are introduced into the VCM 342 substantially uniformly acrossthe area (or portion thereof) defined by the dimensions, therebyillustrating a planar distribution of the particles into the VCM 342.

System with Recapture

FIG. 4 illustrates a system that removes or cleanses a fuel tank 410 orother storage unit of VOC vapors and then recaptures the VOC vapors inliquid form, according to an embodiment of the invention. The system 400includes a capture phase 420, a separator 430, and a recapture container440. The tank 410 may be partially or completely emptied to include fuelor other volatile chemicals such as described with an embodiment ofFIG. 1. Depending on the application, either an active or passiveconnection 418 may be used to interconnect the tank 410 with the capturephase 420. The capture phase 420 may include a container or arrangementof containments that receive VOC vapor from the tank 410.

Accordingly, the capture phase 420 may include a VCM mixture 422 such asdescribed with any of the embodiments provided above. In oneimplementation, for example, the capture phase 420 may correspond to thesystem 300 described with an embodiment of FIG. 3. Thus, the VOC vapormay be particularized and combined with the VCM 422 to create the VCMmixture 424 that is removed from the capture phase 420.

Upon sufficient removal of VOC compounds from tank 410, or alternativelyon saturation of the VCM mixture 424 with VOC compounds, the VCM mixtureis removed from the containment of the capture phase 420. A pump 432 orother driver may be used to remove VCM mixture 424 from the containmentand to drive the fluid mixture into the separator 430.

At the separator 430, an embodiment provides that high pressure nozzles426 spray the liquid VCM mixture 424 into a container 444 or other spacethat comprise the separator 430. The nozzles 426 may create smalldroplets (e.g. 5-10 microns) of the VCM mixture 424. When outputted bynozzles 426, the VCM mixture 424 is separated from the fuel particles,and gravity directs the VCM 422 portion of the mixture 424 downward tosettle at the bottom. A light vacuum may be used to draw out the fuelvapor from the separator 430.

At the same time, the fuel vapor portion 436 of VCM mixture 424 may bedirected to the recovery tank 440, where it is collected in liquid form.Through use of the capture phase 420, the introduction of the VCMmixture 424 into the separator 430 may be regulated, so that a resultingfuel vapor concentration formed in the separator 430 has a steadyconcentration level range of fuel vapor. Nozzles 426 may be positionedso that the vapor portion of the VCM mixture 424 that is introduced intothe separator 430 is provided in vicinity of a pump or light vacuummechanism that draws out the fuel vapor into the recovery tank 440. Inorder to maintain the fuel vapor concentration level at a desired range,one or more embodiments provide that an intake of the separator 430 isbalanced to match the outtake of fuel vapor in the recovery tank 440. Inthis way, the concentration of the fuel vapor in the separator 430remains relatively constant, or at least within a desired range.

In one embodiment, fuel vapor may be drawn out of the separator 430 at arelatively constant flow. Fuel vapor from the separator 430 may besubjected to a stage 432 in which chilling, vacuum, and/or high pressuretakes place, to enhance condensation of the droplets of fuel vapors.

Upon completion, the recovery tank 440 contains fuel 436 from theextracted fuel vapors. The separator 430 includes VCM introduced at thecapture phase 420. The recovery tank 440 may or may not be on-site wherethe system operates. Still further, the recovery tank 440 may optionallybe included with the separator 430.

As another alternative, this recaptured VCM 422 may be re-introducedinto the capture phase 420 via tubing/pipe connection 437. In oneimplementation, the system re-circulates the VCM 422 back into thecapture phase 420 when the system employs drivers or other mechanisms todraw VOCs from the fuel tank 410. This enables a closed and activesystem.

Under another embodiment, however, the system shown in FIG. 4 may becompletely passive, meaning no drivers or moving parts are used. Rather,pressure derived from naturally occurring conditions or other events maybe used to push VOCs from the fuel tank 410 into the capture phase 420and beyond. To maintain the system completely passive, an implementationprovides that the re-circulation of VCM 422, and/or cleansing recoveryfor its reuse in the process being described, occurs off-site. However,such a passive system may not be closed, as would be the case with theactive implementation.

Numerous other capture techniques and systems may be used with anembodiment described. For example, as an alternative to the use ofseparator 430 and recovery tank 440, commercially available systems maybe used.

FIG. 5 illustrates a further embodiment of a VOC recovery system withrecapture capability. The system, generally designated 500, comprises aclosed-loop design that scales particularly well for mobile fieldapplications. A VOC source, such as container 502 feeds VOC-laden vaporto a contactor system 504. The contactor system separates the VOCs fromthe vapor, and recirculates the treated vapor back to the container toeffect closed-loop emission-free operations.

Further referring to FIG. 5, the contactor system 504 employs acontactor vessel 506 formed into a cylindrical and vertically orientedtower. The vessel includes a pneumatic inlet 508 to receive vapor drawnout of the container 502 by a blower 510. A second inlet 512 disposednear the top of the vessel couples to a liquid vapor capture medium(VCM) source 514. A pump 515 draws the VCM from the source and into thecontactor vessel during operation. The VCM preferably comprises a methylester-based liquid, but may include any of the mixtures describedpreviously herein.

The contactor vessel 506 may take a variety of forms, but preferablycomprises a packed tower or tray tower configuration. FIG. 6 illustratesa contactor vessel 600 having a vertically disposed internal tower 602.For packed tower applications, the tower includes a specified volume ofpacking media (not shown) to facilitate entrainment of VOCs from risingvapor introduced via inlet 604 with downwardly flowing VCM providedthrough inlet 606. In tray tower implementations, one or moredisc-shaped trays (not shown) formed with an array of apertures arehorizontally disposed along the tower vertical axis. The trays provide aholding area for the VCM while the vapor bubbles up through the trayopenings. The intimate contact between the vapor and the VCM facilitatedby the packing medium or trays allows Van de Wals molecular bonds toform (between the VOCs and the VCM). The relatively weak bonds arestrong enough to extract the VOCs from the vapor, such that they remainwith the fluid. The methyl esters-based VCM has the capability ofabsorbing at least 5% of its own weight in VOCs before necessitatingreplenishment with clean fluid.

Further referring to FIGS. 5 and 6, for either contact vesselconfiguration, an outlet 610 (516 in FIG. 5) enables contaminated VCMsaturated with VOCs (extracted from the vapor) to exit the vessel forsubsequent distillation (recovery of the purified VCM) by optionallycoupled distillation column 518 (FIG. 5). Distillation may involve anyacceptable form of separation process such as, for example, sparging orthe like. In one embodiment, the distillation column provides purifiedVCM back to the VCM source 514 along a recirculation path 519. To returnVOC-free gas back to the original container 502, the contactor vesselincludes a gas outlet near its apex, at 520 (608 in FIG. 6).

In one specific embodiment, and further referring to FIG. 5, thecontactor system employs a second contactor vessel 522 cascaded inseries with the first vessel 506. The additional vessel providesredundancy and flexibility in system scaling and generally includes thesame inlets and outlets provided with the first contact vessel.

Practical operation of the closed-loop VOC recovery system 500 mayinvolve transporting the contactor system 504 on a mobile sled (notshown) for coupling to a large emptied container. The sled generallyprovides a stable platform for the one or more vertical contactorvessels 506, 522. One or more tanker trucks (not shown) may provide asource of pure vapor capture medium, while an additional tanker truckprovides interim storage for spent VCM until a remotely performeddistillation operation occurs.

Applications

Any of the embodiments described above may be employed with refinery orlarge fuel tanks that can hold hundreds of thousands, or millions ofgallons of fuel when full. With reference to an embodiment of FIG. 1,for example, system 100 may be used in combination with turbines orother active mechanism to withdraw fuel vapors from a fuel tank. In manycases, the concentration of extracted fuel vapor fluctuates too greatlyto be captured with conventional recapture mechanisms. In contrast, anembodiment such as described with FIG. 1 accommodates the VOC vaporcapture outside of the fuel tank, even when the VOC concentrationfluctuates greatly. Many current systems burn off source vapor ratherthan recapture it, in part because of the expense and difficulties inrecapturing, oxidizing or burning fuel vapor which has a concentrationthat ranges from being fuel-rich to being fuel-poor. In contrast, anembodiment such as described provides for the capture of the VOC vaporsoutside of the tank, so as to avoid flaring or burning of the VOCcompounds that is typically performed under conventional approaches.

Still further, other embodiments may be implemented as or on a portablemedium, such as on the back of a flatbed truck or trailer hitch. Whenmade portable, a container system such as described with an embodimentof FIG. 3 may be transported to the site where donative tank(s) that areto be cleansed are located. For refinery implementations, largercontainer systems may be transported using large vehicles.

In an embodiment, recapture of VOC in liquid form may be performedeither on-site or off-site. When performed on-site, the recaptured fuelor VOCs may be returned to the operator of the tank being cleansed. Insome applications, recaptured VOCs may be sold or used as feedstock.

In another embodiment, a system such as described with FIG. 3 or FIG. 4may be integrated or included with vehicle tankers for fuel and/or otherVOCs. In one implementation, a section of a fuel tanker vehicle may beseparated and structured to include, for example, an embodiment such asshown with FIG. 3 or FIG. 4. Other applications that may incorporate oneor more embodiments described herein include vacuum trucks and devicesthat are used control removal of volatile compounds which may be inliquid, solid or vapor form.

As mentioned above, applications for use with embodiments describedherein include cleansing VOC vapors from refineries and large scaletanks, battery tanks for oil drilling operations, storage tanks forindustrial tanks, fuel trucks, marine applications, and airplane fuelbays.

With regard to marine applications in particular, one or moreembodiments contemplate ship-to-ship and ship-to-shore transfers, suchas described in the priority Provisional U.S. Patent Application No.60/871,766. Embodiments described herein include a technique or processfor treating vapor growth in ship-to-ship or ship-to-shore transfers ofpetroleum related compounds. One or more embodiments recognize thetransfer of petroleum compounds causes vapor growth in the receivingvessel that must be balanced currently by recovering the vapor back tothe parent or donating ship. As mentioned with other embodiments, vaporrelease to atmosphere is a regulated event costing large sums in thecase of violation of air quality regulations. Dealing with vapor growthis expensive to the carrier as the time required for transfer iscontrolled by the ability to recover the vapors generated in transferconditions. One or more embodiments include an ability to control andsuppress the vapor growth in this type of transfer on either ship, usingany of the aforementioned embodiments of FIG. 1-4.

Still further, one or more embodiments may align systems such as shownwith FIG. 3 or FIG. 4 in series. In particular, passive variations to anembodiment of FIG. 3 may be arranged in series to achieve a verylow-emission result.

Conclusion

Although illustrative embodiments of the invention have been describedin detail herein with reference to the accompanying drawings, it is tobe understood that the invention is not limited to those preciseembodiments. As such, many modifications and variations will be apparentto practitioners skilled in this art. Accordingly, it is intended thatthe scope of the invention be defined by the following claims and theirequivalents. Furthermore, it is contemplated that a particular featuredescribed either individually or as part of an embodiment can becombined with other individually described features, or parts of otherembodiments, even if the other features and embodiments make nomentioned of the particular feature. Thus, the absence of describingcombinations should not preclude the inventor from claiming rights tosuch combinations.

What is claimed is:
 1. A system for removing volatile organic compoundsfrom a container, the system comprising: an enclosed contactor vesselhaving a first inlet to receive vapor containing volatile organiccompounds from the container; a second inlet to receive a vapor capturemedium from a source; a contactor including an interface to enable thevolatile organic compounds to contact the vapor capture medium; and afirst outlet to, when coupled to the container, recirculate treatedvapor back to the container to effect a closed loop.